Question

During an amateur equestrian event, a 35-year-old woman was thrown from her horse and subsequently kicked in the left flank. She arrives at the emergency department immobilized on a backboard. She is alert but restless and complains of severe abdominal pain. Her temperature is $36.6^\circ\text{C}$ ($97.9^\circ\text{F}$), blood pressure is $82/54\text{ mmHg}$, pulse is $128/\text{min}$, and respirations are $22/\text{min}$. Oxygen saturation is $97\%$ on room air. The airway is patent, and breath sounds are vesicular and symmetric bilaterally. The pelvis is mechanically stable to anteroposterior and lateral compression. The abdomen is distended, with significant ecchymosis over the left flank, and diffuse tenderness with guarding is noted. A focused assessment with sonography for trauma (FAST) demonstrates a substantial anechoic fluid collection in the hepatorenal recess (Morison's pouch) and the splenorenal recess. Intravenous access is established, and rapid infusion of 1 L of warmed crystalloid is initiated. Which of the following is the most appropriate next step in management?